Almost everyone in the building design industry has worked with Leadership in Energy and Environmental Design (LEED), a green building certification program. When it comes to new construction, the credit with the largest potential points is the building’s total energy usage (LEED v4 EA Credit: Optimize Energy Performance). Even if you aren’t pursuing LEED certification, sustainable building design is important, both from its environmental impact and even more importantly, the building’s lifetime costs.

One of the solutions I propose when I hear an owner wants to obtain LEED certification is to include solar. Adding solar satisfies two separate LEED credits: Renewable Energy Production, by creating green energy, and Optimize Energy Performance, by reducing the building’s total energy usage. With the potential gain of 21 points from these two credits, this single solution can get you half way to a LEED certification! Outside of LEED, solar helps your bottom line by reducing your energy bill.

Types of Solar Systems

There are three basic types of solar systems: on-grid, off-grid, and dual (on and off-grid). On-grid is the most common. Your solar panels produce electricity. This electricity is used by your building to offset your normal electrical use. If at any time you produce more than you use, the remainder goes out on the electrical grid. Off-grid is typically found in more rural areas. The solar panels produce electricity that is used right away or stored for later use. The dual system marries these two concepts with power flowing onto the grid or into your usage as well as on-site electrical storage, which is tapped into if normal electricity is lost. During off-grid mode, the storage is recharged by the solar panels, extending your potential run-time.

On-Grid: Components

There are three basic components to any on-grid system. The first are the solar panels. These you can think of as batteries. When the sun shines, they produce a direct current of energy (DC). The second component is an inverter. This is the box that converts the DC electricity to alternating current (AC), which is used by utility companies and what is distributed throughout most buildings. Multiple panels are tied together in series to increase the voltage, and/or tied together in parallel to increase the current, depending on the inverter’s input requirements. The third component is the connection to your building’s distribution grid and, ultimately, the utility company’s electrical grid. Depending on your local utility’s requirements, you may have a production meter to measure your energy production and a disconnect for the system.

Off-Grid: Components

Similar to the on-grid system, the off-grid system contains solar panels as well as an inverter. Since electricity must be used or stored the moment it is produced, this system also has storage. These are typically batteries, but can be anything used to store electricity. A battery charger regulates the current and voltage to and from the batteries. Tying everything together is a battery back-up grid interface. This device is the brains of the system, creating the regulated local electrical grid, directing the electricity to the correct place, and working as a safety check, in case anything goes out of tolerance. As an alternative backup option, a secondary source of electricity – typically a fossil fuel generator – can also be added to the system, depending on the electrical demands, size of storage, size of solar panel arrays and required continual runtime.

Dual on-grid, off-grid: Components

The dual system is the most complicated, tying both ideas into one package. In addition to the components found in the other systems (solar panels, inverter, grid connection, storage, battery charger, battery backup grid interface, generator), this type of system incorporates an automatic transfer switch, with the electrical loads separated into normal-use and critical loads. Under normal use, the grid supplies electricity to your building and the solar array supplements that use. When the grid fails, the battery backup grid interface generates a local grid system, supplying power to all of your building’s critical loads. This setup can again be supplemented with a generator connected through an automatic transfer switch, depending on your needs.

Adding solar to your building can be as simple as placing a few panels on your roof and connecting them to your existing electrical distribution system, or designed to sustain your building through an unexpected loss of normal power. If you are pursuing LEED certification, providing solar as a part of your project will help considerably in achieving your ratings target. Knowing your options will help you make the right decisions.

Thomas Schubert, PE is an electrical engineer with JDB Engineering, Inc. He holds a MS in Electrical Engineering from the Colorado School of Mines and has more than seven years of experience in the design of electrical systems.

Continuing our conversation on industrial energy reduction that started here, we will discuss energy reduction for compressed air and pumping systems.

Compressed air.

This is probably the most expensive form of energy used in an industrial plant because of its poor efficiency – with an efficiency rating of typically 10%. Because of this, compressed air should be high on your target list if it is not already. There are more than a dozen measures that can be considered to reduce energy use for compressed air plants.

Here are three major ones:
1. Reduce leaks
• Typical plants that are poorly maintained have 20-50% leak rates
• Leak repair and maintenance can reduce the leak rate to 10%
• Overall, leak repair could reduce annual consumption by as much as 20%
The most common areas for leaks are couplings, hoses, fittings, regulators, traps, valves, and disconnects. Quick disconnects are notorious for leaking and should be avoided. Detecting methods include manual inspection as well as ultrasonic acoustic detection. Leaks will continue to occur, so detection and correction programs need to be ongoing efforts.

This measure is very interesting when you think about how many processes utilize compressed air within manufacturing plants. Some industry engineers believe this measure has the largest potential for compressed air energy savings, as many operations can be accomplished more economically and efficiently by using other sources.

It seems somewhat obvious, but when walking through mechanical rooms I’m never surprised to find the rooms with air-cooled compressors are super-hot, with compressors utilizing room air, or worse yet, discharging the radiator exhaust air directly to the space! From a design perspective, we always try to duct inlet air directly from the outdoors. The worst case would be that we have the compressor use room air, duct the exhaust to the outside, and ventilate the space very well. In addition, we always try to include a damper arrangement in the exhaust duct to utilize the rejected heat for space heating when needed.

Pumps.

To reduce pump demand, a sound approach is to eliminate bypass loops, which can result in energy savings of 10% to 20%. Constant volume pumping was a traditional approach before the advent of smarter control strategies and capabilities. Although constant volume pumping provides very predictable controls to meet requirements, the energy use is often overlooked. Not surprisingly, there are a lot of these systems still in operation.

Bypass loops are devices that maintain constant flow in the main circuit. For example, a three-way valve serving a chilled water coil allows variable flow through the coil, but maintains constant flow in the main loop. Other similar devices can be in the main circuits. By eliminating these devices, we allow the pumps to operate closer to actual demand and at a lower brakehorsepower, basically riding the pump curve. This is not as efficient as speed drives, but certainly is a step in the right direction.

When properly sizing pumps, it is critical to trim the pump impeller and minimize throttling valves, which can result in energy savings of anywhere from 15% to 20%.

Once we know the design condition (flow and head), we select a pump with the best operating characteristics. For this example, let’s say that we have 600 gpm at 70 ft. head design condition, with a 9”diameter impeller. The balancer goes to balance the pump and realizes he’s getting 750 gpm. What does that mean? The actual pressure drop is less than expected so the pump is over-achieving. To balance to the design flow, the balancer would typically use the triple duty valve to throttle the system to induce additional pressure drop in the system.

Is this energy efficient? Of course not!

Instead, a system curve should be developed using the pump affinity laws and a pump curve to determine what impeller size is really needed. Upon doing so, we find that a smaller impeller would give us the required flow at a much lower brakehorsepower. For this example, the pump would operate at 50% of the brakehorsepower with a trimmed impeller compared to the throttling scheme. Keep in mind, this is not only for new installations. This checkup can be done with any existing pump, knowing the flow demand at full load conditions.

Variable speed drives should also be considered to address variable demand. However, this is not applicable for systems with high static head, open systems, or for systems with extended low-flow conditions.

Variable speed drives are an effective energy measure for pumps with variable demand. Rather than just riding the pump curve as a constant speed pump, pumps with variable speed drivers will continuously match speed and power to actual demand requirements, thus maintaining operational efficiency throughout the pump’s operating range.

Unfortunately, a problem often occurs when we shift from principle into practice. Don’t get me wrong, there are certainly those individuals who turn off the lights when they leave a room, wear a sweater instead of turning up the thermostat, and prefer to drive the speed limit, knowing going any faster would waste fuel. But they are the minority. Most people aren’t motivated by the higher good but by simplicity. “Does saving energy take more effort? Not interested!”

This is why a shift in approach is necessary. Instead of trying to force building users to care enough to take the extra step to save energy, we should instead be making it easy for them to do so. Within the realm of lighting, this could be implementing lighting control systems that incorporate additional energy reduction, require no or minimal extra effort from users, yet doesn’t take away their ability to make lighting choices.

Occupancy vs. Vacancy Sensors

By this point everyone has experienced the occupancy-controlled room. When you enter, the lights turn on automatically. Upon departure, and after a set time, the lights turn off. While this scheme saves energy by eliminating the accidental illumination of an empty room for an evening or more, it also wastes energy when someone pops into the room for a moment or the sensor catches someone walking past it.

Most codes fix this problem with vacancy sensors. Instead of the lighting turning on automatically, with a vacancy sensor the user must press the light switch to turn on the lights. The sensor still works in the vacant case, turning off the lights after a set period of inactivity. This empowers the user to ask themselves if they need the lights on.

On to 50 Percent

Most of us are used to the traditional on-off switch. Flick a switch, and lights turn on to 100% full brightness; flick it the opposite direction, and the room becomes completely dark. Dimming is available, but has always come with an additional cost in any fluorescent fixture. Plus, people quickly learned that if they needed more light, they had to push the diming slider all the way to full lighting; they weren’t thinking about the quantity of light needed, only that they needed it.

A simple, yet powerful control strategy is to default all lights to turn on at 50% of their total output. The user then has the option to remain at the lighting switch, holding down the “on” button for a few seconds to increase the levels up to 100%. This allows for the user to have access to the lighting they need for the task, but also requires them to take a moment to request the extra lighting instead of giving it to them automatically.

Task Lighting

Most indoor spaces are over-lit. This stems from the need to light at a specific level for a specific space, a desk, or a work surface. However, instead of lighting that area, we typically fill the whole room with an equal amount of light. Every task requires a different amount of light, from working on a computer to writing a letter to building a circuit board. We don’t need the same lighting levels to walk to our desk as we do to work at our desk, so why do we provide it?

When designing lighting for a space, we first must understand the function of that space, and then layer lighting to each task. General lighting can be at a lower level, with specific lighting for the tasks being performed. The users should be able to decide when they need the additional lighting – and when it’s not required. Providing vacancy controls integral to the task lighting saves even more energy.

At the end of the day, as lighting design professionals, it is important that we create a new paradigm, and evolve beyond the unsuccessful model of solely relying upon users to make informed decisions to save energy, and instead provide the lighting systems and controls behind the scenes, simplifying the users’ decision-making process.

Thomas Schubert, PE is an electrical engineer with JDB Engineering, Inc. He holds a MS in Electrical Engineering from the Colorado School of Mines and has more than seven years of experience in the design of electrical systems.

The variety of systems and user requirements associated with manufacturing facilities present many challenges, one of which is energy reduction. With these challenges there is opportunity to be creative to find economical and efficient systems that will serve companies well for many years.

Design professionals have a direct impact on energy efficiency, and I feel very strongly that environmental stewardship needs to be a core competency of any firm operating in this market space. As a mechanical engineer, I primarily associate sustainability of MEP systems and industrial buildings with energy reduction.

Why is this?

For starters, here are some of the jaw-dropping statistics about industrial energy:

30% of all greenhouse gas emissions in the United States

37% of all greenhouse gas emissions worldwide

40% of energy use worldwide

If this isn’t horrible enough, as much as 30% of this energy is wasted, costing more than $180 billion annually in the United States alone.

There are many ways to reduce energy. Opportunities range from the “low-hanging fruit” that are straightforward and inexpensive to the more complex and sometimes expensive opportunities that may offer a greater return. So how do you get from here to there when it comes to energy reduction?

It starts with a corporate commitment and a management plan. The ENERGY STAR Guide for Identifying Energy Savings in Manufacturing Plants, sponsored by the EPA, discusses the principals for energy management and provides a comprehensive summary of energy efficient practices and technologies, potential savings, and references to more detailed information. This a very useful document for those operating within the manufacturing sector.

The guide includes two interesting graphics:

Source: US Department of Energy

One thing that certainly doesn’t surprise most industrial users is that motor systems use the greatest amount of electricity. These are the process systems and traditionally represent a point of contention between industrial buildings and LEED certification. In the previous versions of LEED, energy reduction was measured as a whole. That meant as a building designer, I could find ways to reduce the energy efficiency of HVAC systems to a large degree; however, because energy was being evaluated as a whole, including process loads, any energy reduction would be insignificant when compared to the overall energy use of the building.

I like to think of energy categories as “buckets” where energy is being used, and each bucket represents a potential to reduce energy within a manufacturing operation. These buckets include:

Motors

Compressed Air

Pumps

Hot Water and Steam Systems

HVAC

Lighting

Process Integration

Process Heating-Furnaces

Of course it’s hard to classify all the various energy uses of manufacturing plants in a few categories, but these “buckets” offer many opportunities to increase energy efficiency and ultimately reduce energy costs. In reviewing the energy reduction strategies within the guide, I wanted to share my perspective on strategies that are beyond the more common measures, or “low-hanging fruit,” that most manufacturers likely have previously addressed. These are the “mid-hanging fruit,” or items you may turn to after gobbling up the easy measures and ask, “What do we do now?” These items have as much potential, and possibly more, when it comes to reducing energy in your facility.

I certainly cannot cover all items in this post, so this will be the first of several posts addressing this topic. I will start by tackling the Motor category, since they are the main electricity consumer and best place to begin – hey, if you want to make a big impact, attack the biggest factor.

MOTORS

How do you start?…it starts with a plan.

Motor Management Plan: The largest energy user needs managed. You’ll need an inventory and tracking program to document and understand what you have and where it is used, including spares. You’ll need guidelines for proactive repair-and-replace decisions. You’ll need to develop a specification for procuring or repairing motors. And finally you’ll need to develop and implement a predictive and preventative maintenance program. These measures work toward ensuring proper use and application of your motors as well as maintaining motor operating efficiency.

Select Highest Efficiency as Applicable: Select motors strategically by balancing efficiency with the motor’s life cycle cost rather than just first cost and installation costs. Up to 95% of a motor’s cost is actually the energy expense over its life, while purchase, installation, and maintenance costs represent only 5% of total expenses. Premium efficiency motors are most attractive when annual operation exceeds 2000 hours/year. There is a software tool in the Energy Star Guide to assist with motor selection. You may want to also review any available rebates and/or incentives that may positively impact payback times.

Properly Size Motors: It’s plain and simple, motors operate most efficiently when fully loaded. Both efficiency and power factor are reduced at part load. On average, replacing motors properly matched to the loads they serve can save 1% of total motor electricity consumption. An important point here is having a proper spare inventory when replacing motors. I’m sure many times, in a pinch during a failure, an oversized motor is used based on availability. However, they often stay in place far longer than they should, thus increasing energy use and costs.

Consider Variable Speed Drives: Variable speed drives (VSD) can provide energy savings as high as 60% by matching motor speed to the load requirements. In doing so, they will allow motor efficiency to be maintained and only provide the work needed. Note that VSDs are not for every application. The load of the driven equipment must be variable for VSDs to make sense.

Correct Power Factor: While I realize a mechanical engineer talking about power factor is like an electrical engineer explaining the cooling and dehumidifying process, I’ll give it my best shot! Motors are an inductive load measured in KVA. Power is made up of resistive power (KW) and reactive power (KVA). Resistive power, known as active power, is converted to actual work. Therefore, power factor (PF) = KW/KVA. As power factor is reduced due to inefficient motor loadings, the KVA increases, resulting in increased power consumption that usually does not show up in the KW usage. Utilities typically measure and bill KW; however they typically have penalties for low power factor, therefore costing you more money. Power factor can be corrected by reducing inefficient motor loadings, using high efficient or premium efficient motors, and installing capacitors in the AC circuit to reduce the reactive power in the system. Advantages are reduced cost and increased capacity of the electrical distribution system.

In the next post we’ll look at how to reduce the energy use of your compressed air and pump systems.

Adapted from a presentation at the Central Penn Business Journal’s Real Estate & Development Symposium.

Our finale of The Energy Symphony concludes with the topic of preservation and recycling.

Most of us recycle aluminum cans, paper, and plastic and feel good about ourselves. But if you really want to make an impact, what is bigger to recycle than a building?

Unfortunately, in America we still have a throw-away mentality, and it applies to buildings as well:

300,000 buildings will be demolished this year in the United States

600 older and historic homes fell today; 600 more tomorrow, and the day after that…

25-40% of all landfill waste is from building demolition and construction waste

This waste is enough to construct a 30’ high, 30’ wide border around the U.S.

The Brookings Institute estimates that 1/3 of the United States building stock will be gone by 2030 at the current rate of demolition

Do you know what the energy payback is on a new building? Forty years. No matter how many sustainable features a new building has, it will take forty years of building use to offset the energy used to construct it in the first place. This figure jumps to 65 years if another building was torn down to make way for the new building. Yet a lot of buildings only last 20 years – and certainly the life cycle for many of its installed systems is much less than forty or sixty-five years.

So before you think new, think existing. Historic buildings are generally more energy efficient than buildings constructed before 2000! According to a recent General Services Administration study, the Federal government’s “historic” building stock – those constructed prior to 1920 – are 27% more energy efficient than their modern counterparts!

These older buildings were sited based upon sunshine, shade, and wind.

They embrace natural lighting and natural ventilation.

Their windows actually open! And many even have real shutters to keep out the heat and cold!

Thick masonry walls are great insulators and retain heat or cold depending upon the time of year.

Their porches and double vestibules also function to retain heat in the winter and aid ventilation.

Their building products are all natural, with durable first-growth wood, stone, and brick.

And they used locally produced and even recycled materials.

This is what energy efficiency is all about! So if you are building new, think existing first. And if you decide to build new anyway, look at the lessons of the historic buildings to guide your modern building decisions.

Adapted from a presentation at the Central Penn Business Journal’s Real Estate & Development Symposium.

Whether you are building new or undergoing a major renovation, this should be music to your ears: embrace Whole Building Design.

This approach to project delivery integrates the project team from the very early stages of a project. But why would you want to do that?

Doing so significantly increases the probability that there will be an interrelationship between all of the building systems and design disciplines:

HVAC

Architecture

Insulation

Windows

Building siting

etc.

It is important to think of a building “holistically,” rather than as a sum of its parts.

For example, JDB Engineering was involved with a project to renovate a century-old building and convert it for office use. While it would have been easy to just say, “You need a new mechanical system, and here’s the latest and greatest…,” we didn’t look at the heating, ventilating, and air conditioning in a vacuum. Instead, the engineers worked closely with the building architects to study the impact of replacing the windows and adding insulation throughout the building. Our team looked at more than sixteen HVAC options and combinations – what if windows are kept or replaced, or if 1” or 2.5” inches of insulation are added? Ultimately, we analyzed the life cycle costs for eight of those alternatives. The whole team decided that by replacing 185 windows with energy efficient thermal windows, and adding 2.5 inches of spray insulation to the roof and walls, we could significantly reduce the size of the HVAC system and provide an energy efficient solution with a much better payback than if we had worked in a vacuum! Lower first cost + lower operating costs were made possible by embracing the Whole Building Design approach.